Hobbies And Interests
Measuring Forces: Setup
Investigate how the angle of the thread and circumference of the screw affect the mechanical advantage they confer. Measure the circumference and thread angle for a large range of screws. You will need at least 20 different varieties to get useful data. Ideally, use a set with the same thread angle, but with varied circumference and vice versa. Drive the screws half way down through a table. Fit a small clamp over the head of each screw in turn. Hook a Newton meter onto the clamp so that you can pull it horizontally to twist the screw. Join another Newton meter to the tip of the of the screw. You may need to drill a hole in the screw to do this. Position this Newton meter in line with the screw. Attach its free end to a fixed point so that it will be stretched when you turn the screw.
Measuring Forces: Procedure
Pull on the Newton meter joined to the clamp on the screw head to turn it anti-clockwise. Pull until a force of 10 Newtons shows on the Newton meter. Record the number of Newtons registered on the Newton meter joined to the tip of the screw. Do the same for each screw. Mark the results on a scatter graph. Produce one scatter graph showing the influence of screw angle and the other on circumference on the force produced by the screw. If possible, make a three-dimensional graph plotting all three factors in one place.
Archimedes Screw: Setup
An Archimedes screw is onse situated within a pipe. Archimedes developed the device to move water upwards against gravity. The easiest way to build one of these devices is to wrap a coil of pipe around cylinder just as the thread of a screw turns around its body. Use PVC pipe for the cylinder and a clear hose for the tube. Slide a rod down the tube to act as an axle and attach another, shorter rod rod perpendicular to end of the first to stop the pipe slipping off. You can attach it with a screw or a a few coils of wire. Position the end of the hose in a bowl of water, angle the device at a diagonal rising from the bowl and position an empty measuring jug under the other end of the hose.
Archimedes Screw: Procedure
Turn the screw and note how many full rotations are required to draw a cup of water from the bowl to the measuring jug. Now periodically alter the angle at which you wrap the hose around the central cylinder and use a range of different-width cylinders. Keep the angle of the central pipe between the bowl and the jug the same, and use the same width of hose. Note the number of turns required to draw up a cup of water with the different angles and cylinder-width's. Plot the results on scatter plots.